The field of art to which the claimed invention pertains is hydrocarbon separation. More specifically, the claimed invention relates to the separation of a C.sub.9 aromatic isomer from a hydrocarbon feedstream containing a mixture of C.sub.9 aromatic isomers by use of the adsorbent zeolite beta which selectively removes a C.sub.9 aromatic isomer from the feed stream. The selectively adsorbed C.sub.9 aromatic isomer is removed from the adsorbent through a desorption step.